Officers say a man tied to a pole inside an Iowa apartment had a number and letter scratched into his chest.
The Des Moines Register says a neighbor had heard screams on Sunday night.
Officers broke in through a door and found the 24-year-old man lashed to a pole separating the kitchen from the living room.
The man told officers that two men forced their way in that night after he responded to their knock on his door.
He says they threatened him with a knife, tied him to the pole and then used a dental pick to scratch a "5'' and an "M'' into his chest.
He says they eventually took his keys and left.
The man told officers that he didn't know either of his attackers.